One-Pot Synthesis of Bright Blue Luminescent N-Doped GQDs: Optical Properties and Cell Imaging

• Published in: Nanomaterials (Basel, Switzerland) Vol. 11; no. 11; p. 2798
• Main Authors: Wang, Huaidong, Qi, Chong, Yang, Ailing, Wang, Xiaoxu, Xu, Jie
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 22.10.2021; MDPI
• Subjects: Biocompatibility; Bleaching; Carbon; cell imaging; Decay; Decay rate; Excitation; Fluorescence; Fourier transforms; Graphene; Graphite; Medical imaging; Morphology; Nitrogen; nitrogen doped graphene quantum dots; Optical properties; Optoelectronics; pH effects; photo-stability; Photobleaching; Photochemical reactions; Photoluminescence; Photons; Quantum dots; Radiation; Rate constants; Room temperature; Spectroscopy; Surface chemistry; Surface stability; ultrasonic-assisted hydrothermal; United States > US; China; Japan
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano11112798

High fluorescent graphene quantum dots (GQDs) are promising in bioimaging and optoelectronics. In this paper, bright blue fluorescent N-doped GQDs were synthesized using a ultrasonic-assisted hydrothermal method. The morphology, structure, surface chemistry, optical properties, and stability subject to photo-bleaching, temperature, pH and preservation period for the N-GQDs were investigated in detail using various microscopy and spectroscopy techniques. The results showed that the N-GQDs possessed an average size of 2.65 nm, 3.57% N doping, and up to 54% quantum yield (QY). The photoluminescence (PL) spectra of the N-GQDs are excitation dependent when excited in the range of 300–370 nm and excitation independent in the range of 380–500 nm for the core and surface states emission. The N-GQDs showed excellent photo-bleaching resistance and superior photo-stability. At room temperature and in the pH range of 3–8, the fluorescence of the N-GQDs was almost invariable. The N-GQDs can be stably preserved for at least 40 days. The average decay lifetime of the N-GQDs was 2.653 ns, and the radiative and nonradiative decay rate constants were calculated to be 2.04 × 108 s−1 and 1.73 × 108 s−1, respectively. The PL mechanism was qualitatively explained. The N-GQDs was used for cell imaging, and it showed good results, implying great potential applications for bioimaging or biomarking.